On delay device for a visual display unit

ABSTRACT

The invention describes a turn-on delay device ( 10 ) for a visual display unit ( 14 ) which can be placed into an idle state by disabling at least one signal (H-SYNC IN, V-SYNC IN) controlling the visual display unit ( 14 ). The turn-on delay device contains, amongst other things, a disabling device ( 42, 44, 46 ) which disables the signal (H-SYNC IN, V-SYNC IN) for a predetermined delay period. When the delay period has elapsed, the signal (H-SYNC IN, V-SYNC IN) is supplied to the visual display unit ( 14 ).

FIELD OF THE INVENTION

The invention relates to a turn-on delay device for a visual displayunit.

In many areas of public life, for example in the services sector,computer systems are today used which allow a user to performtransactions automatically without having to rely on externalassistance. An example of this is cash dispensing machines at banks,which can be used by a customer of the bank to withdraw money from hisaccount even outside business hours. Such computer systems usuallycontain a central computer to which an input device and a visual displayunit, i.e. a monitor, as an output device, are connected. The user usesthe input device to supply the necessary input information to thecomputer system. The input device used can be a keyboard or a so-calledtouchscreen, for example. A touchscreen is understood as being an inputdevice which is integrated into the screen of the visual display unitand converts touches from the user into input information.

The visual display units used today are generally monitors operating onthe basis of the so-called VGA standard, which condition an analogsignal containing textual and graphics information and display thecorresponding images on their screen. The analog signal is produced inthe computer by a control device which is tuned to the visual displayunit used. A control device tuned to a VGA monitor is also called a VGAgraphics card.

A computer system operated in the manner just described needs, like anyother computer system, to be restarted from time to time when it hasbeen turned off for maintenance work, for example, or when its voltagesupply has been interrupted for other reasons. When the computer isstarted, i.e. when an operating system is loaded into the computer'smain memory, system messages are generally displayed on the screen ofthe visual display unit. No entries must be made using the input devicein this phase, since an error causing the computer system to failcompletely will otherwise be produced in the computer system. Suchsystem failure is also called a “system crash”.

Cash dispensing machines now frequently encounter the problem that auser misinterprets the system messages displayed on the screen of thevisual display unit and makes entries in the computer system's startingphase, for example by touching the touchscreen, which causes the systemcrash just described. Such a system failure generally needs to be putright by a technician, which means that the cash dispensing machine isout of service for a relatively long time.

A known solution to the problem just described is to turn off thevoltage supply of the visual display unit in the starting phase of thecomputer system, with the result that the system messages do not appearon the screen in this phase and the user does not feel encouraged toactuate the input device. If a touchscreen is used as the input device,this solution is not practical, however, since the touchscreen and theinput controller driving it, which is also called a touch controller, issupplied with voltage by the voltage supply for the visual display unit.When the visual display unit is turned off, communication between thecomputer's operating system and the input controller is thusinterrupted, which means that the input controller, and hence thetouchscreen, are not operational when the visual display unit has beenturned on.

SUMMARY OF THE INVENTION

EP-A0 678 843 discloses a method of deactivating a visual display unitin which the visual display unit can be placed into the idle state bydisabling at least one signal controlling said visual display unit, thesignal produced by a control device being disabled for a predetermineddelay period.

The object of the invention is to specify a device which can minimizethe risk of a user who is misguided by the computer system's systemmessages causing the computer system to fail.

The invention achieves this object with a turn-on delay device for avisual display unit which can be placed in an idle state by disabling atleast one signal controlling the visual display unit. The turn-on delaydevice contains at least one input which is connected to a controldevice supplying the signal to it, a disabling device which disables thesignal for a predetermined delay time, and at least one output which isconnected to the visual display unit and supplies the signal to thelatter when the delay time has elapsed.

Modern visual display units generally have a so-called energy-savingfunction which ensures that the visual display units go blank if one ormore control signals are absent. Functioning as control signals areusually a horizontal sync signal and a vertical sync signal, which areproduced by a control device in a computer, e.g. a graphics card, andcoordinate the movement of an electron beam in the visual display unit'spicture tube, with the horizontal sync signal controlling the horizontalflyback and the vertical signal controlling the vertical flyback of theelectron beam as the screen is set up. It is now a provision of theinvention that, connected between the computer's control device and thevisual display unit, there is a turn-on delay device which blocks thecontrol signals for a predetermined delay time when the computer isstarted, so that the screen of the visual display unit is blank whilethe operating system is loaded, and the system messages which areotherwise displayed on the screen are not displayed. In this way, it ispossible to minimize the risk of a user standing in front of the visualdisplay unit feeling prompted by the system messages displayed on thescreen to make entries using an input device, for example a keyboard ora touchscreen, and thus causing the computer system to fail completely.

The invention makes it possible to add further equipment to an existingcomputer system in the manner shown above irrespective of the operatingsystem and of the software used, without needing to make anyconsiderable changes to the computer system. The invention can, inparticular, be applied to all computer systems in which a control deviceoperating on the basis of the VGA standard, i.e. a VGA graphics card,drives a VGA monitor. The connection between the turn-on delay deviceand the computer, on the one hand, and between the turn-on delay deviceand the visual display unit, on the other hand, can be made usingstandard connections, such as D-subminiature plug-ins connections andcorresponding connector receptacles. In one advantageous development ofthe invention, the disabling device contains at least two switches, ofwhich a first switch connects a first input, to which the control devicesupplies a horizontal sync signal, to a first output, and a secondswitch connects a second input, to which the control device supplies avertical sync signal, to a second output. The mutually associated inputsand outputs are accordingly connected to one another directly via arespective switch driven by the disabling device. Advantageously, theswitches can be in the form of CMOS switches. Advantages of the switchesproduced in CMOS technology are low susceptibility to interference, lowspace requirement and high temperature stability.

The disabling device can also contain a timing circuit which turns onthe first and the second switch when the delay time has elapsed.Inexpensive integrated circuits can be used as the timing circuit.

The timing circuit is particularly simple to produce using a monostablemultivibrator. When the computer system is started, the sync signalssupplied to the delay device can switch (as an example) an output,driving the switches, of the multivibrator to its unstable state. Inthis state, the output of the multivibrator causes the switches to beoff and thus causes the sync signals to be disabled. When the delay timehas elapsed, the output of the multivibrator automatically reverts toits stable state and turns on the switches. The sync signals are nowavailable to the visual display unit for setting up the screen. Thedelay time can advantageously be set using a potentiometer.

If a voltage supply fed by the horizontal sync signal is provided in theturn-on delay device, then there is no need for an external voltagesupply or for a voltage supply in the form of a battery. This reducesproduction and operating costs and makes it easier for existing computersystems with the turn-on delay device to have additional equipmentfitted.

To reduce the space requirement of the turn-on delay device, it can beproduced using surface mount technology, also called SMD technology.

According to a further aspect of the invention, a method of deactivatinga visual display unit is specified.

Further advantageous developments of the invention are dealt with in thesubclaims and in the description which follows:

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below with the aid of thefigures, in which:

FIG. 1 shows a schematic illustration of a system comprising a computer,a turn-on delay device and a visual display unit, and

FIG. 2 shows a circuit arrangement for the turn-on delay device shown inFIG. 1.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

The basic way in which the invention works is illustrated in FIG. 1,which shows a turn-on delay device 10 connecting a computer 12 to avisual display unit 14. The components shown in FIG. 1 can be part of asystem used in a bank, for example, to allow a customer of the bank toperform cash transfers or account debits automatically.

The design of the computer 12 and of the visual display unit 14 and theway in which they work are known per se, so that the description ofthese components can be kept brief at this point.

The computer 12 can be a personal computer of known type having aninterface 16 for connecting the visual display unit 14. The computer 12also contains a controller 18, for example in the form of a plug-ingraphics card, which conditions the textual and graphics informationprocessed in the computer for the visual display unit 14. In theillustrative embodiment to be explained, the controller 18 is a VGAgraphics card which converts the textual and graphics information intoan analog signal and supplies it to the visual display unit 14, which,for its part, operates on the basis of the VGA standard.

The visual display unit 14 contains a screen 20 having an integratedinput device 21, also called a touchscreen, which a customer of the bankcan use to make entries by touching the screen 20. The visual displayunit 14 also has an input controller 22, i.e. a touch controller, fordriving the touchscreen, and a voltage supply 22.

In known systems, a connecting cable 26 coming from the visual displayunit 14 is connected directly to the interface 16 of the computer 12.The connection between the connecting cable 26 and the interface 16 isusually made using a standardized plug-in connection. Thus, for example,the connecting cable 26 is provided with a conventional 15-pinD-subminiature connector 28 which, in a system based on the prior art,is plugged into a corresponding connector receptacle 30 on the interface16 of the computer 12.

The system shown in FIG. 1 is distinguished from the prior art by theturn-on delay device 10, which is connected between the computer 12 andthe visual display unit 14. On the turn-on delay device 10, there is aconnector receptacle 32 which matches the D-subminiature connector 28 onthe connecting cable 26 and can be identical to the connector receptacle30 on the interface 16 of the computer 12. The D-subminiature connector28 on the connecting cable 26 is plugged into the connector receptacle32 on the turn-on delay device 10. In place of the connecting cable 26from the visual display unit 14, a connecting cable 34 is connected tothe connector receptacle 30 on the interface 16 using a D-subminiatureconnector 36. The connecting cable 34 can be permanently attached to ahousing of the turn-on delay device 10.

The VGA graphics card 18 produces a plurality of control signals whichare necessary for showing an image in the visual display unit 14 and ofwhich FIG. 1 shows only a horizontal sync signal H-SYNC IN and avertical sync signal V-SYNC IN. The sync signals H-SYNC IN, V-SYNC INare supplied via the connecting cable 34 to the turn-on delay device 10,are disabled there (as is yet to be described) for a predetermined delaytime in the starting phase of the computer, and are switched through tothe visual display unit 14 when this delay time has elapsed. In FIG. 1,the switched-through sync signals are called H-SYNC OUT and V-SYNC OUT.The sync signals H-SYNC OUT and V-SYNC OUT coordinate the movement of anelectron beam in a picture tube (not shown in FIG. 1) in the visualdisplay unit 14.

The visual display unit 14 has an energy-saving function as providednowadays in VGA monitors. If the visual display unit 14 registers theabsence of the sync signals H-SYNC OUT and V-SYNC OUT, it is placed inan idle state, where, by way of example, its screen 20 goes blank. Thetechnical precautions necessary for this purpose on the visual displayunit 14 are known per se and are therefore not explained further at thispoint. The essential thing is that the visual display unit 14 reacts, inthe manner just described, to the absence of the sync signals H-SYNC OUTand V-SYNC OUT.

FIG. 2 shows a possible circuit arrangement for the turn-on delay device10, which switches through the sync signals H-SYNC IN and V-SYNC INproduced by the controller 18 to the visual display unit 14 when asettable disabled time has elapsed after the computer 12 has been turnedon or restarted. The circuit arrangement shown in FIG. 2 contains afunctional unit which builds up the voltage supply for the turn-on delaydevice 10 in a manner which is yet to be described. This functional unitcomprises the resistors R1, R2, R3, R7, the diodes D1, D2, D3, thecapacitors C1, C2, C3, and the switch 40. A timing circuit 42 forms afurther functional unit with the resistors R4, R6, the potentiometer R5and the capacitors C4 and C5. In the illustrative embodiment beingexplained, the timing circuit 42 is an ICM7555IBA-type integratedcircuit, operated as a monostable multivibrator. The other componentsshown in FIG. 2 and connected to the timing circuit 42 are the resistorsR8, R9, R10, the capacitor C6 and the switches 44, 46 and 48. Thesecomponents can also be essentially regarded as a functional unit.

The switch 40 and further switches 44, 46, 48 are combined in a quadswitch 50. The quad switch 50 is produced in CMOS technology and is inthe form of an HEF4066BT-type integrated circuit. The circuitarrangement shown in FIG. 2 also contains inputs 52, 54, 56 and outputs58, 60, 62. The inputs 52, 54, 56 are to be allocated to the connectorreceptacle 30 and the outputs 58, 60, 62 are to be allocated to theD-subminiature connector 28 shown in FIG. 1.

The sync signals H-SYNC IN, V-SYNC IN produced by the VGA graphics card18 are supplied to the turn-on delay device 10 via the inputs 52 and 54,respectively. The input 56 and the output 62 of the turn-on delay device10 are grounded (GND).

The way in which the circuit arrangement shown in FIG. 2 works isexplained below. In the phase in which the graphics card 18 is still notproducing any sync signals H-SYNC IN and V-SYNC IN, there is no signalpresent at the inputs 52 and 54 of the turn-on delay device 10. Theswitches 44, 46 of the integrated circuit 50 are off at this instant.When the sync signals H-SYNC IN and V-SYNC IN appear at the inputs 52,54, the voltage supply is built up in the turn-on delay device 10 byutilizing the energy supplied to the turn-on delay device 10 in the formof the sync signal H-SYNC IN. For this purpose, the sync signal H-SYNCIN is supplied to the functional unit mentioned initially, whichcomprises resistors R1, R2, R3, the diodes D1, D2, D3 and the capacitorsC1, C2, C3, as well as the switch 40 with the resistor R7 connectedupstream of it. The resistors R1, R2, R3, R7 are used for currentlimiting, and the diodes D1, D2 and D3 produce smoothed DC voltages fromthe sync signal H-SYNC IN, which is an AC voltage signal, in combinationwith the capacitors C1, C2, C3. If the voltage at an input 64 of theswitch 40 reaches a predetermined value, the switch 40 turns on, and thevoltage supply is built up. Since the voltage required for operating theturn-on delay device 10 is provided by the sync signals H-SYNC IN andV-SYNC IN, there is no need for an external voltage supply or for avoltage supply in the form of a battery.

When the voltage supply has been produced in the turn-on delay device 10in the manner just described, the timing circuit 42 operated as amonostable multivibrator is started via an input 2 which has an RCcombination comprising the resistor R6 and the capacitor C5 connectedupstream of it. At this moment, an output 3 of the timing circuit 42 ischanged to an unstable state, which continues for a predetermined delaytime. In this phase, the duration of which is defined by the resistorR4, the capacitor C4 and the potentiometer R5, the switches 44, 46remain off. When the delay time has elapsed, the output 3 of the timingcircuit 42 reverts to a stable state and turns on the switches 44, 46 inthe integrated circuit 50 via the resistors R8, R9, R10, the capacitorC6 and the switch 48. The sync signals H-SYNC IN and V-SYNC IN are nowswitched through to the outputs 58 and 60 of the turn-on delay device 10by the switches 44, 46 and are thus available to the visual display unit14. The switched-through sync signals are called H-SYNC OUT and V-SYNCOUT in FIG. 2. The setup of the screen can finally be completed in thevisual display unit 14 using the sync signals H-SYNC OUT and V-SYNC OUT.

The delay time after which the timing circuit 42 operated as amonostable multivibrator turns on the switches 44, 46 via its output 3is equivalent to the disabled time, in which the screen 20 of the visualdisplay unit 14 goes blank after the operating system of the computer 10is started. This delay time can be set at the potentiometer R5, whoseresistance value can be set externally using a screwdriver, for example.In the illustrative embodiment shown in FIG. 2, the delay time can beset to a value between 0.5 and 5 minutes.

The invention is not restricted to the circuit arrangement shown in FIG.2, which should merely be regarded as a specific illustrativeembodiment. The dimensional design of the components used in the circuitarrangement shown in FIG. 2 is suited to the sync signals H-SYNC IN andV-SYNC IN as produced by the VGA graphics card 18. For the illustrativeembodiment shown in FIG. 2, the components have the followingdimensions:

R1=680, R2=1.8 k, R3 22=k, R4=22 k, R5 to 1 M, R6=1 M, R7=100 k, R8=1 M,R=100 k, R10=1.8 k, C1:1 F/16 V, C2:10 F/16 V, C3:1 F/16 V, C4:100 F/10V, C5:100 nF/50 V, C6:100 nF/50 V.

The capacitors C2 and C4 are electrolytic capacitors having the polarityindicated in FIG. 2. The diodes D1 and D2 used are BAR43S-type diodesand the diode D3 used is a BAR42-type diode.

List of Reference Symbols

10 Turn-on delay device

12 Computer

14 Visual display unit

16 Interface

18 Controller

20, 21 Screen with integrated input device

22 Input controller

24 Voltage supply for the visual display unit

26 Connecting cable

28 D-subminiature connector

30 Connector receptacle

32 Connector receptacle

34 Connecting cable

36 D-subminiature connector

40 Switch

42 Timing circuit

44 Switch

46 Switch

48 Switch

50 Quad switch

52 Input

54 Input

56 Input

58 Output

60 Output

62 Output

R1 to R10 Resistors

C1 to C6 Capacitors

D1, D2, D3 Diodes

What is claimed is:
 1. A turn-on delay device (10) for a visual displayunit (14) which can be placed in an idle state by disabling at least onesignal (H-SYNC IN, V-SYNC IN) controlling the visual display unit (14),said device comprising at least one input (52, 54) which is connected toa control device (18) supplying the signal (H-SYNC IN, V-SYNC IN) to it,a disabling device (42, 44, 46) which disables the signal (H-SYNC IN,V-SYNC IN) for a predetermined delay time, and at least one output (58,60) which is connected to the visual display unit (14) and supplies thesignal to the latter when the delay time (H-SYNC OUT, V-SYNC OUT) haselapsed.
 2. The turn-on delay device (10) as claimed in claim 1, whereinthe disabling device contains at least two switches (44, 46), of which afirst switch (44) connects a first input (52), to which the controldevice supplies a horizontal sync signal (H-SYNC IN), to a first output(58), and a second switch (46) connects a second input (54), to whichthe control device supplies a vertical sync signal (V-SYNC IN), to asecond output (60).
 3. The turn-on delay device (10) as claimed in claim2, wherein the switches (44, 46) are in the form of CMOS switches. 4.The turn-on delay device (10) as claimed in claim 2, or 3, characterizedin that the disabling device contains a timing circuit (42) which turnson the first and the second switch (44, 46) when the delay time haselapsed.
 5. The turn-on delay device (10) as claimed in claim 4, whereinthe timing circuit (42) is a monostable multivibrator.
 6. The turn-ondelay device (10) as claimed in claim 4, and further comprising apotentiometer (R5), connected upstream of the timing circuit (42), forsetting the delay time.
 7. The turn-on delay device (10) as claimed inclaim 2, and further comprising a voltage supply fed by the horizontalsync signal (H-SYNC IN).
 8. The turn-on delay device (10) as claimed inclaim 7, wherein the voltage supply has means (D1 to D3, C1 to C3) forrectifying and smoothing the horizontal sync signal (H-SYNC IN).
 9. Theturn-on delay device (10) as claimed in claim 1, wherein said device isproduced using surface mount technology.
 10. The turn-on delay device(10) as claimed in claim 1, wherein said device is for a VGA visualdisplay unit.
 11. A method of deactivating a visual display unit (14)which can be placed in an idle state by disabling at least one signal(H-SYNC IN, V-SYNC IN) controlling the visual display unit (14), whereinthe signal (H-SYNC IN, V-SYNC IN) produced by a control device (18) isdisabled for a predetermined delay period, and the signal (H-SYNC IN,V-SYNC IN) is enabled and supplied to the visual display unit (14) whenthe delay time has elapsed.